Propeller type unit heaters are typically utilized to heat large open areas. Units are designed to be installed a minimum of 8 feet high and are available with optional downturn nozzles to assist in directing the air to the floor. Propeller unit heaters should never be used with any type of discharge duct work. Available in sizes from 30 to 400 MBH.
lower units are typically installed where discharge duct work is utilized or operating noise is an issue. Similar to the propeller type units except a centrifugal blower is used to over come the static pressure of the duct work.
Duct Furnaces are utilized in applications where the airflow is provided by a separate air handler. Typically utilized in "built up" type system. A stainless steel heat exchanger is recommended for systems utilizing a cooling coil.